1989 Chevy S-10 missing

OUTSIDERDGN

MEMBER
1989 CHEVROLET S-10
4 CYL
2WD
MANUAL
106,295 MILES

My truck will start missing going up any grade of hill
but sometimes it wont and nothing I do will change the problem.
i have changed the erg valve, a complete tune up, coil, computer, oxygen sencer, throttle postion sencer, map sencer, temp sencer, rebuilt the throttle body, and it still starts missing when I drive up hill after I top the hill it will stop missing again.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Test for excessive backpressure on the exhaust system to rule out a clogged catalytic converter

Other probable causes:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires